Presently, a portable terminal of electronic instruments such as cellular phones, PDAs (Personal Digital Assistants) and the like is loaded with a small and thin imaging unit. Such an imaging unit is generally equipped with a solid state imaging device such as a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) image sensor and the like, and a lens for forming a subject image on the solid state imaging device.
With reduction in size and thickness of a portable terminal, reduction in size and thickness of an imaging unit is requested. For lowering the cost of a portable terminal, an efficient production process is desired. As the method of producing a lot of such small lenses, there is known a method in which a wafer level lens having a constitution containing a plurality of lenses molded on a substrate is produced, and the substrate is cut to separate the plurality of lenses, to produce a lot of lens modules.
There is also known a method in which a substrate carrying a plurality of lenses formed thereon and sensor substrate carrying a plurality of solid state imaging devices formed thereof are integrally combined, and the substrate and the sensor substrate are together cut so as to include the lens and the solid stage imaging device as a set, to produce a lot of imaging units.
In the past, examples of the wafer level lens include those shown in the following patent documents.
A patent document 1 (JP-A-2005-539276) describes the constitution of a multi-layered wafer level lens obtained by laminating substrates carrying a plurality of lenses formed thereon.
A patent document 2 (WO-07/107,025) describes a method of feeding a molding material on a substrate, and molding a lens on the substrate using a mold.